Oil burner with elongated flame chamber



0. A. DAVIS, SR

Nov. 19, 1968 OIL BURNER WITH ELONGATED FLAME CHAMBER Sheets-Sheet 1Filed April 24, 1964 INVENTOR.

ORVIS A. DAVIS, SR.

ATTORNEY Nov. 19, 1968 DAVIS, 9R 3,411,859

OIL BURNER WITH ELONGATED FLAME CHAMBER Filed April 24, 1964 2Sheets-Sheet 2 1 v. 98 402 loa I06) I04 o d o 0 55 8 6 5 INVENTOR. ORVISA. DAVIS, SR.

ATTORNEY United States Patent 3,411,859 OIL BURNER WITH ELONGATED FLAMECHAMBER Orvis A. Davis, Sr., Gibsonia, Pa., assignor to Gulf Research &Development Company, Pittsburgh, Pa. Continuation-impart of applicationSer. No. 70,226, Nov. 18, 1960. This application Apr. 24, 1964, Ser. No.362,302

1 Claim. (Cl. 431-287) This application is a continuation-in-part ofcopending Ser. No. 70,226, filed Nov. 18, 1960, which is now US. Patent3,131,749.

This invention relates to oil burner apparatus employing an aspiratingtype nozzle.

The flame produced upon ignition of the spray from the nozzle to whichliquid fuel is pumped under pressure has the general characteristics ofbeing widely dispersed, having a deep yellow coloration and beingextremely smoky. In order to produce a flame of improved characteristicsfrom this type of nozzle it is necessary for the nozzle to have such arestricted orifice that it generally becomes inoperative due toplugging. On the other hand, a flame of sharply improved characteristicsis produced by employing for liquid fuels aspirating type nozzleswherein an aspirating gas such as air or steam and preferably air passesthrough the nozzle in a manner which creates a suction thereby drawingliquid fuel into the nozzle which admixes with the air to form anatomized fuelair mixture. The air or other gas used to aspirate oil intosuch nozzles is employed at the low pressure of about 2 to pounds persquare inch gauge while the oil is made available to the nozzle at onlyatmospheric pressure. Advantageously, the oil is drawn into the nozzlefrom a level lower than the nozzle so that the oil reaches the nozzlepurely by the aspirational effect of the air passing therethrough.

Aspirating nozzles for liquid fuel preferably employ a frusto-conicalswirl stern possessing slanted peripheral grooves and disposed insealing engagement with a corresponding surface inside the nozzleburner. The grooves constitute ducts leading into a swirl chamberwhereby a swirling motion is imparted to the aspirating air passingtherethrough en route to the swirl chamber. The swirl chamber has anaxial discharge orifice restriction at the end opposite the swirl stemand an oil inlet duct extends axially into the swirl chamber a portionof distance from the swirl stem to the discharge orifice. The aspiratingair swirling through the swirl chamber draws oil into itself to form amixture of fuel and air. The air-oil mixture from the swirl chamber ispassed through the discharge orifice of the nozzle and upon ignitionburns as a compact, elongated, high velocity flame.

Other constructions can be employed in place of a swirl stem forswirling the aspirating air. For example, the aspirating air can beadmitted tangentially to a swirl chamber which is circular in transversecross section through a wall opening. However, no matter what swirlingmeans is employed, when an axial oil inlet duct is employed it mustextend at least to an intermediate point along the length of the swirlchamber or else the aspirating gas will not aspirate sufficient oil intothe swirl chamber to form a combustible mixture.

The compact, elongated, high velocity flame from the aspirating nozzleburns with a light yellow coloration. The base of the flame starts at apoint just slightly outside the discharge orifice of the nozzle and inthe case of a nozzle employing air at about 3 pounds per square inchgauge pressure drawing into the nozzle about 0.15 gallon of oil per hourthis flame extends for about 12 inches and averages about 1 to 3 inchesin diameter. In accordance with this invention an apparatus has beendeveloped to be 3,41 1,859 Patented Nov. 19, 1968 employed incombination with such a nozzle for sharply altering the flamecharacteristics. When employing the apparatus of this invention with anaspirating nozzle instead of burning as a high velocity jet the sprayfrom the nozzle is caused to burn uniformly through perforations on thetop of an elongated manifold with the characteristics of a flame whichwould be produced it low pressure gaseous fuel were being passed throughthe manifold. The apparatus of this invention thereby converts the highvelocity, light yellowish, jet type flame to a gently waiting lowvelocity flame with a light blue hue rising uniformly from perforationsalong the length of an elongated manifold.

The structure of the apparatus of this invention will be readilyunderstood by reference to the attached drawings in which FIGURE 1 showsthe details of a preferred aspirating nozzle and FIGURES 2, 3, 4, 5 and6 show details of apparatus to be employed in combination with anaspirating nozzle adapted to alter the characteristics of the flame fromsuch a nozzle in the manner described.

Referring to FIGURE 1, a longitudinal cross-sectional view of a nozzledesignated generally as 10 is shown having a tubular body portion 12which is internally and externally threaded as shown. The forward end ofbody portion 12 terminates with a substantially flat integral enclosure14 which is on a plane transverse to the axis of tubular body 12.Enclosure 14 has an axial tapered central orifice opening 16. Orificeplate 18 immediately inside of and adjacent to enclosure 14 has anover-all diameter less than the internal diameter of tubular body 12 andhas an axial orifice 20. Orifice 20 is the apex of an axial conical bore60 as shown. The diameter orifice opening 16 is larger than the diameterof orifice opening 20 and a duct 62 extends from orifice 20 to partiallyobstruct the entrance to orifice 16. The forwardly protruding peripheralrim 22 of orifice plate 18 contains one or more borings 24 which open ina tangential manner into swirl chamber 58 which is formed by virture ofrim 22 setting apart the rearward surface of enclosure 14 and theforward surface of orifice plate 18.

A plug 26 having external threads and an axial bore 28 is equipped withtwo or more prongs 30 on its rear face so that it can be screwed intothe interior of tubular body 12 and urge orifice plate 18 in sealingengagement against the inner surface of enclosure 14 so that orificeopening 20 is axially disposed. Plug 26 has a central forwardlyprojecting stud 32 terminating with a frusto-conical swirl stem 34 whichholds orifice plate 18 in place by abutting firmly against thecomplementary internal surface of the base portion of conical bore 60leaving unoccupied the apex of conical bore 60, the unoccupied apex ofconical bore 60 constituting a swirl chamber 40. Swirl stem 34 isequipped with one or more peripheral slots 36 extending the length ofthe stern and providing passage betw en air chamber 38 and swirl chamber40. Slots 36 are generally comparable in cross section and length withborings 24 so that the pressure drop through each is generally the same.In one example, slots .030 inch square are employed. Bore 28 which iscoaxial with tubular body 12 constitutes a connecting passageway for thesuction of oil from an oil reservoir on a lower level, not shown, intoswirl chamber 40. Bore 28 is extended through a portion of the length ofswirl chamber 40 by means of tube 61.

After the orifice plate 18 is secured in position by tightly screwingplug 26 into place as shown in FIGURE 1, the entire resulting nozzleassembly is secured into position for use by screwing tubular body 12into wall 42 of the flame chambers shown in FIGURES 2, 3, 4 and 5. Afterthe nozzle is assembled and secured into place, an oil reservoir on alevel lower than the nozzle is connected to the nozzle at externallythreaded boss 44 extending rearwardly from the center of plug 26 andcoaxial with oil passageway 28. Suitable flared tubing 46 extends frombelow the level of oil in the reservoir and is attached in sealingconnection to boss 44 by means of nut 48. Passage of compressed air tochamber 38 is provided by passageway 50 through plug 26 terminating withrearwardly extending externally threaded boss 52 to which flared tubing54 is attached in sealing connection by means of internally threaded nut56.

In operating the nozzle shown in FIGURE 1 air under a pressure betweenabout 2 and pounds per square inch gauge, pressures in the upper portionof this range being employed when it is desired to aspirate greaterquantities of fuel oil than are aspirated at air pressures in the lowerportion of this range, is charged to air chamber 38 from which it passesthrough groove 36 and enters swirl chamber 40 substantially tangentiallyand swirls in swirl chamber 40. The swirling air draws oil from areservoir which is on a lower level than the nozzle by suction throughpassageway 28 into swirl chamber 40 where a fuel-air mixture is formedwhich passes through orifice and duct 62 to a second orifice 16. Tube 61allows the air to assume an adequate swirling pattern prior toaspirating in oil and prevents air back pressure against the oil fromthe reservoir. Secondary air from air chamber 38 passes throughtangential inlet ducts 24 to second swirl chamber 58 from which itswirls through orifice 16 where it increases in velocity and aspiratesinto itself the fuel-air mixture from duct 62 to form a new mixture inwhich the oil is more highly atomized and which is richer in air. Thenew mixture is discharged in a swirling pattern through orifice opening16.

It has been found that ducts 61 and 62, which project axially a portionof the distance into each swirl chamber, are essential to operation ofthe nozzle and in the absence of either or both of these ducts the airwas unable to aspirate sufficient oil into itself to create a mixture ofoil and air capable of sustaining combustion.

In FIGURE 2 aspirating nozzle 10 is shown supported centrally of andextending through end wall 42 at the outer end of burner chamber 70.Nozzle 10 is supplied with aspirating air under a pressure between about2 and 10 pounds per square inch gauge through tube 54 and is suppliedwith oil under atmospheric pressure by aspiration through tube 46.Extending rearwardly from end wall 42 and coaxial with nozzle 10 areinner and outer cylinders 72 and 74, respectively, defining an annularspace 76 between them. Annular space 76 is enclosed on its rearward endby a circular plate 82 and on its forward end opens through aperture 80into zone 78 of combustion chamber 70.

A collar 84 is in threaded engagement with cylinder 74 and is adapted toadjust the openings of air inlet ports 86 extending through cylinder 74.Such adjustment regulates the amount of air available for combustion ofthe spray from nozzle 10 in addition to the aspirating air which reachesthe nozzle through tube 54. It is noted that suflicient air should passthrough ports 86 to prevent flame extinguishment but not suflicient airfor complete combustion, allowing ambient air to satisfy combustionrequirements above perforations 108 as will be apparent hereinafter. Ifdesired, means can be utilized for directing ambient air to the zoneabove perforations 108. The air entering through ports 86 travelsforwardly through annular space 76 and aperture 80 into the zone 78 fromwhich it travels through the perforations in flame tube 88, beingprevented by means of plate 90 from passing lengthwise through tube 70except through flame tube 88.

Flame tube 88 extends forwardly from end wall 42 coaxially surroundingnozzle 10 and is of a smaller diameter than the inner diameter ofaperture 80 whereby the secondary air enters combustion chamber 70 onthe outside of flame tube 88 so that in its inward travel through theperforations in flame tube 88 it serves to confine the spray from nozzle10. The end of flame tube 88 is coextensive with respect to theperiphery of opening 94 through which the flame from nozzle 10 passes inits travel to central passageway 96 of combustion chamber 70. Passageway96 is indicated in FIGURE 3. If desired, plate 90 can be entirelyomitted from the a paratus, in which case aperture is disposed radiallyinwardly of flame tube 88 to direct air flow longitudinally into theinterior of flame tube 88 at the nozzle end of the flame tube withoutsaid air first traveling through the perforations in flame tube 88.

Referring to FIGURE 3, central passageway 96 is defined between a pairof parallel baflies 98 extending from plate the major portion of thelength of the chamber 70. As shown in FIGURE 3, plate 90 is a transversebarrier within flame chamber 70 and disposed near the rearward end offlame chamber 70. Bafl'les 98 terminate before the pair of flamedeflectors 100 which are disposed at the forwardmost or inner end ofcombustion chamber 70. Baflies 98 also define a pair of elongated outerchambers 102 between themselves and side walls 104 of combustion chamber70. Combustion chamber 70 is provided with a top enclosure 106 shown inpartially cut away view and having two rows of elongated opening meanssuch as perforated openings 108. One row of perforated openings 108extends adjacent to one of the longest sides of top enclosure 106 whilethe other row extends adjacent to the opposite of the longest sides oftop enclosure 106 and each is located so as to be disposed substantiallycentrally of each of corresponding zones 102.

The flame produced upon ignition of the spray from nozzle 10 by means ofa suitable igniter, not shown, is supplied with auxiliary air from ports86 and travels through opening 94 along the length of central zone 96which extends substantially the length of the flame. The igniter can bedisposed at any location within the burner, for example, inside centralzone 96 close to flame tube 88. The flame is divided into approximatelytwo equal portions at flame deflectors 100 each portion being deflectedsideways and backwards through the side chambers 102. A wafting flamesimilar in appearance to that of a low pressure gaseous fuel rises fromthe perforations 108 so that two rows of flame of a soft blue hueappears at the top of burner chamber 70, the columns of flamerespectively extending along each of the longest sides of the burnerchamber 70.

A difliculty which sometimes arises in operation of the flame chambershown in FIGURE 3 is that the height of the flame emerging from theperforations 108 is highest at the perforations closest to the forwardend of burner chamber 70 and the height of the flame uniformlydiminishes so as to be barely perceptible at the perforations closest tothe rearward end of burner chamber 70. This difficulty is advantageouslycorrected by means of the embodiment shown in FIGURE 4 and is mostadvantageously corrected by means of the embodiment shown in FIGURE 5.

As shown in FIGURE 4 flame chamber 70 is provided with two parallel rowsof louvers 110 in place of solid batfles 98. Louvers 110 may beotherwise described as slatted panels or slanted bafiles. Louvers 110are slanted so that passages between adjacent louvers extend outwardlyand rearwardly from central zone 96 whereby the flame passing fromnozzle 10 through the longitudinal central zone 96 is not deflected intransit and whereby the gases in side zones 102 which are movingcountercurrently to the gases in central zone 96 are likewise notdeflected in transit. The zone 96 and zones 102 are sufii ciently narrowin relation to the flame so that the passage of the flame throughcentral zone 96 creates an aspirational effect through the louvers 110whereby the flame reaching deflectors 100 tends to be drawn back theentire length of side zones 102. Such is evidenced by the observationthat the height of the flame rising from perforations 108 issubstantially uniform in each row of 5 perforations along the entirelength of combustion chamber 70.

Combustion chamber 72 shown in elevation in FIG- URE 5 in combinationwith the louvers 100 of FIG- URE 4 represents the most preferredembodiment of this invention. Combustion chamber 72 is tapered in themanner shown so that its height becomes uniformly smaller withincreasing distance from the nozzle end. It is noted that the taper inthe embodiment of FIGURE 5 is accomplished with the top of the chamber72 remaining horizontal so that the plurality of flames from chamber 72will rise to a common horizontal plane. Also, the two rows of louvers110 in FIGURE 5 can uniformly approach each other with increasingdistance from the nozzle. It is seen that if the chamber 70 of FIGURE 4is altered to possess the taper of chamber 72 of FIG- URE 5, the innerzone 96 through which the flame from the nozzle passes becomes uniformlysmaller in transverse cross section with increasing distance from thenozzle thereby tending to sharply increase the velocity of flame gasesin the region of deflectors 100 and thereby giving added impetus to themovement of combustion gases countercurrently through side zones 102.The combination of increased velocity due to the tapered configurationof combustion chamber 72 and the aspirational effect due to the louvers110 produces a highly uniform flame in each row of perforations 108along the entire length of the combustion chamber so that there is noperceptible difference in flame height, intensity or color from theperforations at one end of either row of perforations to the oppositeend.

Louvers 110 in addition to providing an aspirational effect tending todraw combustion gases the entire length of side zones 102 as shown inFIGURE 4 tend to serve still another advantageous function in that wihlegases in the side zones 102 tend to rise through the openings 108 at thetop of the combustion chamber and burn in passage through these openingsany entrained and unburned droplets of oil, being too heavy to risethrough openings 108. tend to be drawn through the slatted openings inlouvers 110 back to chamber 96 thereby avoiding buildup of oily depositsand soot in the apparatus.

FIGURE 6 shows a preferred construction for a top plate for thecombustion chamber apparatus of this invention. As shown in FIGURE 6 topplate 112 has each row of perforations 108 on a plane inclined so thatthe flames rising from the opposite rows tend to intercept each other.This provides the advantage that furnace walls, or other equipment arenot subjected to a direct or even glancing flame. It was found thatdirecting each row of flame to each other in this manner caused theflame to assume a yellow discoloration evidencing incomplete combustionbut this was corrected by employing a baflle 114 between the two rows ofopenings 108 whereupon the flame again assumed its light bluecoloration.

Various changes and modifications may be made without departing from thespirit of this invention and the scope thereof as defined in thefollowing claim.

I claim:

1. An apparatus comprising in combination an elongated flame chamber andan aspirating nozzle having a discharge orifice, a transverse barrierdisposed within said elongated flame chamber near its rearward enddefining a smaller rearward section and a larger forward section in saidflame chamber, an opening centrally located on said transverse barrier,a perforated duct coaxial with said central opening extending betweensaid transverse barrier and the opposing wall of said rearward section,passage means at a point in said rearward section outside of saidperforated duct for the admission of air to said rearward section, saidnozzle disposed so that its discharge orifice is directed coaxially intosaid perforated duct, a pair of elongated parallel baflles within saidlarger section of said flame chamber defining within said larger sectiona central elongated zone to which access is provided by said centralopening and side elongated zones extending along each side of saidcentral zone, access means between said central zone and each of saidside zones at the forward end of said forward section of said flamechamber, and elongated opening means extending along the top of saidside zones.

References Cited UNITED STATES PATENTS 2,040,558 5/1936 Lukemeier158-114 2,041,706 5/1936 Hahn 158-99 2,189,532 2/1940 Garson et a1 1581X 2,469,272 5/1949 Logan 158-281 2,755,851 7/1956 Dow et al. 1581142,844,195 7/1958 Wein 158--28.1 2,869,626 1/1959 Sherman 26319 X2,870,830 1/1959 Schwank 158-114 3,124,193 3/1964 Klein 158-28.13,131,749 5/1964 Davis 158-4 FOREIGN PATENTS 520,240 11/1953 Belgium.

586,223 10/ 1933 Germany.

825,859 12/1959 Great Britain.

147,174 10/ 1954 Sweden.

FREDERICK L. MATTESON, JR., Primary Examiner.

R. A. DUA, Assistant Examiner.

1. AN APPARATUS COMPRISING IN COMBINATION AN ELONGATED FLAME CHAMBER ANDAN ASPIRATING NOZZLE HAVING A DISCHARGE ORIFICE, A TRANSVERSE BARRIERDISPOSED WITHIN SAID ELONGATED FLAME CHAMBER NEAR ITS REARWARD ENDDEFINING A SMALLER REARWARD SECTION AND A LARGER FORWARD SECTION IN SAIDFLAME CHAMBER, AN OPENING CENTRALLY LOCATED ON SAID TRANSVERSE BARRIER,A PERFORATED DUCT COAXIAL WITH SAID CENTRAL OPENING EXTENDING BETWEENSAID TRANSVERSE BARRIER AND THE OPPOSING WALL OF SAID REARWARD SECTION,PASSAGE MEANS AT A POINT IN SAID REARWARD SECTION OUTSIDE OF SAIDPERFORATED DUCT FOR THE ADMISSION OF AIR TO SAID REARWARD SECTION, SAIDNOZZLE DISPOSED TO THAT ITS DISCHARGE ORIFICE IS DIRECTED COAXIALLY INTOSAID PERFORATED DUCT, A PAIR OF ELONGATED PARALLEL BAFFLES WITHIN SAIDLARGER SECTION OF SAID FLANGE CHAMBER DEFINING WITHIN SAID LARGERSECTION A CENTRAL ELONGATED ZONE TO WHICH ACCESS IS PROVIDED BY SAIDCENTRAL OPENING AND SIDE ELONGATED ZONES EXTENDING ALONG EACH SIDE OFSAID CENTRAL ZONE, ACCESS MEANS BETWEEN SAID CENTRAL ZONE EACH OF SAISSIDE ZONES AT THE FORWARD END OF SAID FORWARD SECTION OF SAID FLAMECHAMBER, AND ELONGATED OPENING MEANS EXTENDING ALONG THE TOP OF SAIDSIDE ZONES.